WO2007077599A1 - Receiver apparatus and communication system - Google Patents

Abstract

A receiver apparatus and a communication system wherein the frequency usage efficiency is raised to improve the communication throughput. The receiver apparatus comprises a receiving means that receives multicarrier signals in which a plurality of subcarriers are divided into a plurality of subcarrier blocks (frequency blocks) each including at least one subcarrier and in which signals to be transmitted to receiver apparatuses are arranged in those subcarrier blocks; an estimating means that estimates, for each of the subcarrier blocks, quality values indicative of the reception statuses of the signals arranged in the subcarrier blocks; and a notifying means that notifies a transmitter apparatus of information indicative of a high quality subcarrier block having a higher quality value than the other ones of the quality values, also notifies it of the quality value in the high quality subcarrier block, and further notifies it of the intervals of the subcarrier blocks each having a quality value the difference of which from the quality value in the high quality subcarrier block do not go beyond a predetermined threshold value.

Description

 Specification

 Receiving apparatus and communication system

 Technical field

 [0001] The present invention relates to a receiving apparatus and a communication system for adaptively performing frequency allocation in a multicarrier transmission scheme.

 Background art

 In recent years, the OFDM (Orthogonal Frequency Division Multiplexing) method has been adopted for transmission methods of various communication systems to realize high-speed data communication with high frequency utilization efficiency. The OFDM scheme is a scheme in which transmission data is divided into a plurality of pieces, and the divided transmission data is mapped to a plurality of orthogonal carrier waves (subcarriers) and transmitted in parallel on the frequency axis.

 [0003] Each receiving device of a communication system using such a multi-carrier transmission scheme has a different frequency band affected by frequency selective fusing due to a difference in receiving environment. Therefore, a method of increasing cell throughput of the entire communication system by performing scheduling such that each transmitting apparatus is less susceptible to fading as much as possible, and is assigned to each frequency band (subcarrier). Has been proposed.

 [0004] Frequency scheduling used in such a multi-carrier transmission scheme such as OFDM will be described below with reference to Figs. FIG. 10 is a diagram illustrating an example of frequency selective fading, and FIG. 11 is a diagram illustrating an example of frequency scheduling. Specifically, FIG. 10 shows the state of frequency selective fading in the time block from time 2T to 3T in FIG.

 In the example shown in FIG. 10, the signal received by the receiving device of user 1 is the highest signal-to-noise ratio (hereinafter referred to as “subcarrier block (frequency block) f 1” from time 2T to 3T. The signal received by the user's receiving device has the highest SNR and the SNR in the subcarrier block f4.

[0006] In this case, the transmitting apparatus, as shown in FIG. The subcarrier block fl having NR is scheduled to be assigned to the transmission data for user 1 and the subcarrier block f4 is assigned to the transmission data for user 2.

 [0007] Thus, in order to perform appropriate frequency scheduling in a transmission device, it is necessary for the transmission device to accurately know reception environments such as reception SNR in each reception device. Because of this need, a method is adopted in which each receiving device feeds back its own receiving environment to the transmitting device.

 [0008] However, in the case of a communication system in which a plurality of receiving apparatuses are used as communication partners with one transmitting apparatus, all receiving apparatuses feed back received SNRs related to all subcarrier blocks to the transmitting apparatus. This will greatly increase the resource consumption of the feedback link. As a result, the frequency utilization efficiency is lowered, and as a result, there is a problem that the throughput of data transmission through the feedback link is lowered.

 [0009] In order to solve such a problem, each receiving apparatus feeds back only the positions of N subcarrier blocks to the transmitting apparatus in order from the received subcarrier block having the highest average SNR. Therefore, a method of reducing the amount of feedback information has been proposed (see Non-Patent Document 1 below). FIG. 12 is a diagram showing the concept of such feedback information generation according to the prior art.

 FIG. 12 shows an example in which the communication frequency band is divided into 18 subcarrier blocks. The receiving device feeds back the top 5 (#nl force # n5 shown in Fig. 13) among the average SNR of each subcarrier block by frequency selective fading. At this time, for example, the receiving apparatus feeds back the SNR in each subcarrier block (SN R (nl), SNR (n2), SNR (n3), SNR (n4), SNR (n5))).

 Non-patent literature 1: Zhong- Hai rian, Yong-Hwan Lee, “Opportunistic scheduling with partial channel information in OFDMA / FDD systems”, VTC2004— Fall. 2004 IEEE 60th Volume 1, 26-29 Sept. 2004, P511-514 Vol.1

 Disclosure of the invention

 Problems to be solved by the invention

[0011] However, in the above-described conventional technology, the SNR is increased from the maximum SNR! / N in order, and N SNRs are fed back in order. However, in order to realize precise frequency scheduling. However, since the number of feedback (N) needs to be increased to some extent, the amount of feed knock information cannot be reduced sufficiently.

[0012] The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a receiving apparatus and a communication system that improve frequency use efficiency and improve communication throughput.

 Means for solving the problem

 The present invention employs the following configuration in order to solve the above-described problems. That is, the present invention is divided into a plurality of subcarrier blocks (frequency blocks) including a plurality of subcarrier powers and at least one subcarrier, and signals to each receiving apparatus are arranged in units of the subcarrier blocks. A receiving means for receiving a multicarrier signal, an estimating means for estimating a quality value indicating a reception state of a signal arranged in each subcarrier block for each subcarrier block, and a higher quality value among the quality values. Information on the high-quality subcarrier block, the quality value in the high-quality subcarrier block, and the section of the subcarrier block having a quality value in which the difference between the quality value in the high-quality subcarrier block is within a predetermined threshold A receiving device comprising notification means for notifying the transmitting device of

 [0014] In the present invention, each receiving apparatus relates to a multicarrier signal in which a plurality of subcarriers are divided into a plurality of subcarrier blocks including at least one subcarrier. In the transmitting apparatus, each receiving apparatus is assigned to each receiving subcarrier block. Information to be considered when allocating the transmission signal to is notified.

 [0015] The notified information is generated based on a quality value indicating a reception state of a signal arranged in each subcarrier block of the received multicarrier signal. That is, the notified information includes information indicating a high quality subcarrier block having a high quality value among the estimated quality values of each subcarrier block, the quality value in the high quality subcarrier block, and the high quality The subcarrier block is generated so that a difference from the quality value in the subcarrier block includes a section of the subcarrier block having a quality value within a predetermined threshold.

Here, the information indicating the subcarrier block is, for example, information regarding the position of the subcarrier block, and is a block number for specifying the subcarrier block. There may be. The quality value is, for example, a value indicating a signal-to-noise ratio (SNR).

[0017] Thus, in the present invention, the information regarding the high-quality subcarrier block having the high quality value (the quality value is set as the minimum necessary information without the reception apparatus sending the quality value for all the subcarrier blocks. And a subcarrier block section based on a predetermined threshold based on the high quality subcarrier block is notified.

[0018] Thereby, in the base station apparatus, the general property of frequency selective fusing that guarantees a good reception environment over a wide frequency region near a subcarrier block with good reception quality. Based on the above, it is possible to estimate reception environment information such as quality values for the other subcarrier blocks based on the information about the high quality subcarrier blocks.

 Therefore, according to the present invention, it is possible to suppress the amount of notification information from the receiving device to the transmitting device, and to provide accurate receiving environment information of each receiving device to the transmitting device. become. As a result, even when a communication system composed of the receiving device and the transmitting device is considered, the frequency utilization efficiency of the entire system can be improved and the communication throughput can be improved.

 [0020] Further, as a section of a subcarrier block having a quality value in which a difference from a quality value in a high quality subcarrier block, which is notified by the notification means, is within a predetermined threshold, a subcarrier included in the section is included. The information indicating the subcarrier block having the minimum frequency band in the block and the information indicating the subcarrier block having the maximum frequency band may be notified.

 [0021] With this, as long as the transmission apparatus knows information about the predetermined threshold value in the reception apparatus, the transmission apparatus has a quality value whose difference from the quality value in the high quality subcarrier block is within the predetermined threshold value. The quality value for the carrier block can be estimated

[0022] Therefore, according to the present invention, since it is only necessary to notify information indicating the target subcarrier block, it is possible to further reduce the amount of information of notification information to the transmitting apparatus.

[0023] Further, the notification means includes the information indicating the subcarrier block having the minimum frequency band and the information indicating the subcarrier block having the maximum frequency band, together with the maximum frequency band. The quality value in the subcarrier block having the small frequency band and the quality value in the subcarrier block having the maximum frequency band may also be notified.

 [0024] Thus, the transmitting apparatus that has received the notification can more accurately estimate the reception state in the receiving apparatus.

 [0025] In addition to the above-described configuration, the present invention may further include dispersion estimation means for estimating delay dispersion of the received multicarrier signal. In this case, the notification means should change to the section of the subcarrier block and notify the delay dispersion estimated by the dispersion estimation means.

 [0026] In the present invention, in addition to the quality value in the high quality subcarrier block, information indicating the high quality subcarrier block, delay dispersion is notified to the transmission apparatus.

 [0027] Thereby, the transmission device can detect the spread of the quality value for the subcarrier blocks around the frequency band of the high quality subcarrier block by the delay dispersion, so that such a high quality subcarrier block can be detected. It is possible to estimate the quality value of a high-quality subcarrier block without being notified of the quality value individually for the subcarrier blocks around the frequency band of the.

 [0028] Thus, according to the present invention, the transmission device can estimate accurate reception information even when the reception device receives a small amount of information.

 [0029] Further, according to the present invention, the notifying unit is configured such that the difference between the quality value in the high-quality subcarrier block and the quality value in each subcarrier block is a frequency band power far or frequency band of the high-quality subcarrier block. There may be further provided generating means for generating the difference information represented by the amount of information as the number of subcarrier blocks having is smaller. In this case, the notification unit may notify the transmission apparatus of this difference information instead of the section of the subcarrier block.

 [0030] In the present invention, the difference information in which the difference from the quality value in the high-quality subcarrier block related to the subcarrier block around the frequency band of the high-quality subcarrier block is represented by a predetermined amount of information is Information indicating the high quality subcarrier block and the quality value of the high quality subcarrier block are notified to the transmitting apparatus.

[0031] Further, the difference information includes the frequency band power of the high quality subcarrier block. A subcarrier block having a wave number band is generated so as to have a smaller amount of information.

 [0032] With this, the transmitting apparatus that has received the above information estimates the quality information in the subcarrier blocks around the frequency band of the high quality subcarrier block by knowing information about the amount of information represented by the difference information. Will be able to.

 [0033] As described above, according to the present invention, the quality value around the high-quality subcarrier block having a high quality value can be notified to the transmission device with a small amount of information. It is possible to accurately notify the reception status of the receiving device while suppressing the amount of notification information.

 [0034] Further, according to the present invention, the quality value related to each subcarrier block in each receiving device is estimated based on the information notified to each receiving device, and the estimated quality value is calculated. Originally, even when a signal to each receiving apparatus is arranged in units of the subcarrier block, the transmission apparatus may preferentially arrange a signal to a receiving apparatus having a high quality value with respect to the target subcarrier block. is there.

 [0035] That is, in the feedback information in which the amount of information is suppressed by the receiving device according to the present invention described above, the transmitting device can accurately grasp the reception state in each receiving device. It is.

 [0036] Therefore, the present invention can also be applied to a communication system including the above-described receiving apparatus and transmitting apparatus.

 [0037] Further, the present invention provides a communication method and an information processing apparatus (computer) having the same characteristics as those of the above-described receiving apparatus and transmitting apparatus according to the present invention as the receiving apparatus and transmitting apparatus according to the present invention. It can be realized as a functioning program or a recording medium on which the program is recorded. In addition, the reception device and the transmission device according to the present invention are, for example, a communication device that communicates with each other wirelessly, a communication device that performs communication by wire, or an interface signal in a computer. May be a device, an element, etc.

[0038] Note that the present invention relates to signal allocation to subcarrier blocks, that is, focuses on frequency scheduling, and does not limit time scheduling on the time axis at all! /. The invention's effect

 [0039] According to the present invention, it is possible to provide a receiving device, a communication system, and a communication method that increase frequency utilization efficiency and improve communication throughput.

 Brief Description of Drawings

 FIG. 1 is a diagram showing a functional configuration of a base station apparatus (transmitting apparatus) in the embodiment.

 FIG. 2 is a diagram showing a configuration example of an OFDM frame.

 FIG. 3 is a diagram showing a configuration example of a subcarrier (frequency) block.

 FIG. 4 is a diagram showing a functional configuration of a mobile terminal (receiving device) in the embodiment.

 FIG. 5 is a diagram showing a concept of frequency selective fusing and reception environment information generation in the embodiment.

 FIG. 6 is a diagram showing a processing flow related to user assignment.

 [FIG. 7] FIG. 7 is a diagram showing a concept of frequency selective fusing and reception environment information generation in the first modification.

 [FIG. 8] FIG. 8 is a diagram showing a concept of frequency selective fusing and reception environment information generation in the second modified example.

 [FIG. 9] FIG. 9 is a diagram showing a concept of frequency selective fusing and reception environment information generation in the third modified example.

 FIG. 10 is a diagram showing an example of frequency selective fuzzing.

 FIG. 11 is a diagram showing an example of frequency scheduling.

 FIG. 12 is a diagram showing the concept of feedback information generation according to the prior art. Explanation of symbols

[0041] 10 pilot multiplexing section

 11, 43 Serial Z parallel (SZP) converter

 12 IDFT

 13, 45 Parallel Z-serial (PZS) converter

 14, 52 Digital Z analog (DZA) converter

 15, 51 Up-conversion section

21, 41 Down conversion section 22, 42 Analog Z digital (AZD) converter

 23 Feedback information extractor

 24 User allocation section

 44 DFT 咅

 47 Signal-to-noise ratio (SNR) estimator

 53 Feedback information generator

 BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, a communication system having a reception device and a transmission device according to an embodiment of the present invention will be described with reference to the drawings. In the following description, for convenience of explanation, the receiving device and the transmitting device in the present embodiment will be described as separate communication devices. However, the present invention is not limited to such a configuration, and is described below. It may be a communication device having both functions and transmission functions.

 [0043] In this embodiment, a mobile terminal is taken as an example of a receiving device, and a base station device that performs radio communication with a plurality of mobile terminals is taken as an example of a transmitting device. These communication devices shall have a function capable of realizing the OFDM system as a multi-carrier transmission system. In addition, the communication device in the present embodiment may be a power line communication device that performs communication by wire, a device that performs communication as an interface signal in a computer, an element, or the like. The configurations of the following embodiments are merely examples, and the present invention is not limited to the configurations of the embodiments.

 [Transmission device]

 First, a base station apparatus as a transmission apparatus in the present embodiment will be described. Hereinafter, the functional configuration of the base station apparatus in the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a functional configuration of the base station apparatus.

[0045] The base station apparatus includes a pilot multiplexing unit 10, a serial Z parallel (hereinafter referred to as SZP) conversion unit 11, an IDFT unit 12, a parallel Z serial (hereinafter referred to as PZS) conversion unit 13, and a digital Z. Analog (hereinafter referred to as DZA) conversion unit 14, up-conversion unit 15, down-conversion unit 21, analog Z-digital (hereinafter referred to as AZD) conversion unit 22, feedback information extraction unit 23, user allocation unit 24, etc. Have. [0046] The pilot multiplexing unit 10 receives a data signal to be transmitted (including a control signal and the like) from the user allocation unit 24. When the pilot multiplexing unit 10 receives the pilot signal together with the data signal, the pilot multiplexing unit 10 receives the data signal and pilot signal based on the OFDM frame A serial signal sequence arranged at the position of is generated. Here, the OFDM frame configuration will be briefly described with reference to FIG. FIG. 2 is a diagram showing an example of an OFDM frame configuration in the present embodiment.

 [0047] The OFDM frame in this embodiment has N subcarrier powers for each frame.

 In each frame, a pilot signal, a data signal, and the like are arranged at predetermined positions. In Fig. 2, P1 to PN indicate pilot signals, and Da (b) (a is 2 to 10, b is 1 to N) is a cc data signal allocated to the b subcarrier of the a symbol in each frame. Show. Note that the present invention does not limit the OFDM frame to the configuration shown in FIG.

[0048] The SZP conversion unit 11 converts the serial signal sequence generated by the pilot multiplexing unit 10 into parallel signals arranged in parallel for the number of subcarriers (N).

 C

 [0049] The IDFT unit 12 performs IDFT processing on the parallel signal output from the SZP conversion unit 11 in units of OFDM symbols. Normally, the IDFT size N used in this IDFT processing is larger than the effective number of subcarriers (N), so the IDFT unit 12 is configured to input N parameters.

 C C

 Set the zero (0) signal in the remaining N + 1 to N sections of the real signal, for a total of N parallel

 IDFT processing is performed on the signal.

 [0050] The signal TE (f) on the time axis of each subcarrier output from the IDFT unit 12 is combined and multiplexed by the PZS conversion unit 13, and a guard interval is added by a guard interval adding unit (not shown) or the like. Then, it is converted into an analog signal by the DZA converter 14. The converted analog signal is converted from the center frequency of the signal to a radio transmission frequency by the up-conversion unit 15 and transmitted from the antenna element.

 [0051] On the other hand, the base station apparatus receives reception environment information of each mobile terminal from a plurality of mobile terminals that are communication partners. The received reception environment information is processed by the following functional units. Details of the contents of the reception environment information will be described later. In the present embodiment, the reception environment information is simply transmitted by wireless communication. However, the present invention provides a method for transmitting the reception environment information to each mobile terminal power base station apparatus. Not limited.

[0052] The radio frequency signal including the reception environment information is received by the antenna element and downloaded. Conversion unit 21 converts the signal into a baseband signal. This baseband signal is converted into a digital signal by the AZD conversion unit 22 and then input to the feedback information extraction unit 23.

 [0053] The feedback information extraction unit 23 acquires the reception environment information of each mobile terminal from the input signal. The feedback information extraction unit 23 acquires reception environment information regarding each of a plurality of mobile terminals that are communication partners.

 [0054] Based on the reception environment information regarding each mobile terminal passed from the feedback information extraction unit 23, the user allocation unit 24 selects which user of the data signals for each mobile terminal (user) that has received the transmission request. Data signal can be sent to any subcarrier block (frequency block)

V,) is scheduled for transmission (hereinafter, this process is also referred to as user allocation process). The user allocation unit 24 divides N subcarriers into a plurality of subcarrier blocks.

 C

 The user allocation process is performed for each subcarrier block.

 [0055] The method for setting the number of subcarrier blocks N to the number of subcarriers N is particularly limited

 C fblk

 However, it should be optimized according to the installation environment of the communication device. Also,

If N> N, N does not need to be an integer multiple of N and each block is different

C fblk C fblk

 It may be configured by the number of subcarriers. Also, the subcarrier block configuration may be previously set as a fixed value between the transmission device and the reception device, and the configuration of the subcarrier block is made variable, and the transmission device power is notified to the reception device. You may do so.

 [0056] In the present embodiment, N is an integer multiple of N, and each subcarrier block has N /

 C fblk C

The configuration includes N subcarriers. Figure 3 shows the subcarrier fblk in this embodiment.

 It is a figure which shows the structural example of a rear block. As shown in FIG. 3, in the present embodiment, subcarrier N is divided by the number of subcarrier blocks N, and one subcarrier block is divided into 4 subcarrier blocks.

C fblk

 Consists of carriers.

Note that the details of the user allocation process in the user allocation unit 24 will be described in the section <User allocation process>. The user allocation unit 24 generates a data signal in which transmission signals to users are adaptively allocated to a predetermined arrangement of transmission frames. User allocation part ₂

4 passes the generated data signal to the pilot multiplexing unit 10. [Reception device]

 Hereinafter, a mobile terminal as a receiving apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing a functional configuration of the mobile terminal in the present embodiment.

 [0059] The mobile terminal in this embodiment includes a down-conversion unit 41, an AZD conversion unit 42, an S ZP conversion unit 43, a DFT unit 44, a PZS conversion unit 45, a signal-to-noise ratio (hereinafter referred to as SNR (Signal to Noise Ratio)). And an estimation unit 47, an up-conversion unit 51, a DZA conversion unit 52, a feedback information generation unit 53, and the like.

 [0060] When the antenna element receives a radio transmission frequency signal composed of the above-described OFDM frame, the down-conversion unit 41 converts the radio transmission frequency signal into a baseband signal. This baseband signal is converted into a digital signal by the AZD conversion unit 42, and then converted into an N-sample parallel signal having the same IDFT size in the base station apparatus by the S / P conversion unit 43. At this time, the normal signal strength guard interval is removed.

 [0061] The DFT unit 44 performs DFT processing on the input parallel signal, and outputs N signals corresponding to each subcarrier component. The DFT size used in this DFT process is the same as the IDFT size used in the transmitting device. At this time, N + 1 to N signals among the output N signals are zero signals set by the base station apparatus. this

 C

 The output parallel signals are rearranged into a serial signal sequence by the PZS conversion unit 45 and passed to other functional units (for example, a demodulation unit). The output parallel signal is also passed to the SNR estimation unit 47.

 [0062] SNR estimation section 47 estimates the average SNR of each subcarrier block based on the signal sequence corresponding to each subcarrier passed from DFT section 44. This average SNR may be obtained, for example, by obtaining the SNR of each subcarrier constituting the target subcarrier block and averaging them. Information such as the number of subcarriers constituting each subcarrier block may be stored in a memory or the like in the mobile terminal, or the base station apparatus power may be notified in advance. The estimated average SNR is passed to the feedback information generation unit 53.

[0063] The feedback information generating unit 53 is based on the average SNR of each passed subcarrier block. Next, reception environment information for feedback to the base station apparatus is generated. The reception environment information generation process is described in the section <Reception environment information generation process>.

 The generated reception environment information is converted into an analog signal by the DZA conversion unit 52. The converted analog signal is converted from the center frequency of the signal to a radio transmission frequency by the up-conversion unit 51 and transmitted from the antenna element.

 [0065] In this embodiment, the frequency / time conversion process is IDFT, and the time / frequency conversion process is DFT. The present invention is not limited to these, and the frequency / time conversion process is IFFT, One frequency conversion processing may be FFT. In addition, any method may be used for transmitting the reception environment information from the mobile terminal to the base station apparatus.

 [0066] <Reception environment information generation process>

 Hereinafter, reception environment information generation processing in the mobile terminal will be described with reference to FIG. FIG. 5 is a diagram showing the concept of frequency selective fading and reception environment information generation.

 [0067] The mobile terminal receives a signal affected by frequency selective fading as shown in FIG. When the SNR estimation unit 47 of the mobile terminal receives a signal sequence corresponding to each subcarrier with respect to the signal affected by the fading, an average SNR of each subcarrier block (hereinafter simply referred to as SNR). Is estimated. In Fig. 5, each bar (square) represents a subcarrier block.

 [0068] Based on the SNR for each subcarrier block, feedback information generation section 53 generates reception environment information as follows. First, the feedback information generation unit 53 detects the subcarrier block number having the maximum SNR medium SNR for each subcarrier block (subcarrier block #n in FIG. 5).

[0069] Next, feedback information generating section 53 detects the subcarrier block number of the subcarrier block having an SNR that is also within a predetermined threshold (-X decibel (dB)). The feedback information generation unit 53 detects the numbers of the subcarrier block having the minimum frequency band and the subcarrier block having the maximum frequency band among the detected subcarrier blocks (subcarrier blocks # ηθ and # in FIG. 5). nl). This predetermined threshold value (XdB) may be stored in advance in a memory or the like in the mobile terminal as a fixed value common to the system, and may be notified as control information from the base station apparatus. May be.

 [0070] The feedback information generation unit 53 determines the maximum SNR value (SNR (n)), the subcarrier block number (n), the subcarrier block number (ηθ) of the detected minimum frequency, and the maximum frequency. The reception environment information including the wave number subcarrier block number (nl) is generated. In this embodiment, the reception environment information is generated based on the subcarrier block having the maximum SNR. However, the reception environment information is not limited to the maximum SNR, and is close to the maximum SNR and is based on the subcarrier block having the SNR. You can do it.

 [0071] <User assignment process>

 When the base station apparatus receives a signal including the reception environment information (n, SNR (n), nO, nl) described above, the feedback information extraction unit 23 extracts the reception environment information and assigns the user allocation. Passed to part 24.

 [0072] Upon receiving the reception environment information (n, SNR (n), nO, nl) for each mobile terminal in this way, the user allocation unit 24 also obtains the ηθ force for each mobile terminal based on this reception environment information. Estimate the SNR for each subcarrier block in the interval.

 [0073] In the estimation of SNR for each subcarrier block, SNR (nO) = SNR (n) —X, SNR (nl) = SNR (n) Estimate —X, and estimate the SNR for other subcarrier blocks as shown in (Equation 1) below.

 [0074] [Equation 1]

_SN 2 {(nk) xSNR (n0) ₊ (kn), SNR (n)}

 n-n0 + l

_{SNR (k) =} {(k → SNR (nl) ₊ (nl-k), SNR (n)} (^)) (Equation ¹ )

nl-n + i Then, the user allocating unit 24 holds the estimated information to execute the user allocation process for each mobile terminal. With regard to this user allocation process, techniques such as MAX-CI and proportional fair are generally known, and the present invention may use these misalignment techniques or other techniques. For example, in the user allocation process based on MAX-CI, the user with the highest SNR among the SNRs for each subcarrier block fed back by the reception environment information. The is assigned to the subcarrier block. For the subcarrier block for which no SNR based on the reception environment information exists, the average SNR is the highest among the average SNR of each user, and the user is assigned.

 [0075] Fig. 6 shows the processing flow for user assignment based on this MAX-CI. In the processing flow shown in FIG. 6, first, it is checked whether or not there is an SNR estimated based on the reception environment information for each subcarrier block (S601). If it is determined that there is an SNR for any mobile terminal for the target subcarrier block (S601; YES), the mobile terminal having the maximum SNR is selected from the SNRs, and the mobile terminal is selected as the target subcarrier block. Allocate to carrier block (S602).

 [0076] On the other hand, when it is determined that there is no SNR for the target subcarrier block

 (S601: NO), an average SNR that is an average value of the SNR is obtained for each mobile terminal, and the mobile terminal having the maximum average SNR is assigned to the target subcarrier block (S603).

 [0077] When the user allocation for the target subcarrier block is completed, the next subcarrier block is targeted (S604), and the above-described processing is performed for all subcarrier blocks (S605).

 <Operation in Embodiment Z Effect>

 In the base station device (transmitting device) and mobile terminal (receiving device) in this embodiment, N

 C

 Multi-carrier signal consisting of N subcarriers, and the N subcarriers

 c

 Folk into N subcarrier blocks (frequency blocks) each consisting of 4 subcarriers

 The signal is divided and data signals to each mobile terminal are transmitted and received in units of the subcarrier blocks.

 [0079] In each mobile terminal, when the above-described multicarrier signal affected by frequency selective fading is received, SNR estimation section 47 estimates the SNR for each subcarrier block of the received signal. .

[0080] Subsequently, feedback information generating section 53 generates reception environment information based on the SNR related to each subcarrier block. This reception environment information includes the subcarrier block number (n) of the subcarrier block with the largest SNR among the SNRs for each subcarrier block. The subcarrier block having the minimum frequency band and the subcarrier block having the maximum frequency band among the subcarrier blocks having an SNR whose difference from the maximum SNR is within a predetermined threshold (one XdB) Included. The generated reception environment information is transmitted to the base station apparatus.

 [0081] The base station apparatus receives the reception environment information of each of a plurality of mobile terminals that are communication partners. In the base station apparatus that has received the reception environment information, the SNR of each subcarrier block in each mobile terminal is estimated based on the reception environment information. In this SNR estimation, a predetermined threshold (XdB) that the base station apparatus has in common with a plurality of mobile terminals is used.

 [0082] Then, when the SNR of each subcarrier block for each mobile terminal is estimated, transmission is performed based on the estimated SNR to the mobile terminal having a high SNR for each subcarrier block in the transmission signal. Should be preferentially placed. The multicarrier signal in which the data signal is arranged in this way is transmitted to a plurality of mobile terminals.

 [0083] As described above, in this embodiment, each mobile terminal transmits information on subcarrier blocks having the maximum SNR (including the SNR value) as the minimum necessary information without sending SNRs for all subcarrier blocks. ) And the subcarrier block section based on the subcarrier block. In the base station apparatus, the SNRs for the other subcarrier blocks are estimated based on the information about the subcarrier blocks having the maximum SNR.

 [0084] This is because, compared to the effect of frequency selective fading, the width of one subcarrier block is relatively small, and therefore the SNR change of each subcarrier block tends to be gradual. This is based on the idea that a good reception environment is guaranteed over a wide frequency range near the subcarrier block.

 [0085] Thus, according to the present embodiment, adaptive frequency allocation based on accurate reception environment information can be realized while suppressing the amount of feedback link information. As a whole communication system composed of mobile terminals, the frequency utilization efficiency can be increased and the communication throughput can be improved.

[0086] [First Modification] In the reception environment information generation method and user allocation process in the present embodiment described above, the mobile terminal and the base station apparatus each share a predetermined threshold (XdB), and the mobile terminal has an SNR within this threshold as well as the maximum SNR force. The subcarrier block (ηθ) having the lowest frequency and the subcarrier block (nl) having the highest frequency are notified respectively, but the base station apparatus does not have this threshold information, and the mobile terminal power is subcarrier. Instead of the block numbers ηθ and nl, the SNR in the subcarrier block ηθ and the SNR in the subcarrier block nl may be notified to the base station device (see FIG. 7).

 [0087] In this case, although the amount of reception environment information increases compared to this embodiment, the SNR (n 0) and SNR (nl) are estimated to be SNR (n) and the threshold X force, which is more accurate than Therefore, it is possible to estimate the SNR in the nl interval from ηθ more accurately.

 [Second Modification]

 In the reception environment information generation method and the user allocation process in the above-described embodiment, the mobile terminal uses a predetermined threshold (XdB), and the differential power of the maximum SNR power is information on the subcarrier block having an SNR within this threshold. In addition to the maximum SNR and its subcarrier block number (n), the mobile terminal force may notify the base station apparatus of information on delay dispersion. Hereinafter, the reception environment information generation process of the mobile terminal and the user allocation process of the base station apparatus in the second modification will be described. In addition, the functional configurations of the mobile terminal and the base station apparatus are the same as those in the above-described embodiment.

 [0089] <Receiving environment information generation process>

 Hereinafter, reception environment information generation processing in the mobile terminal will be described with reference to FIG. FIG. 8 is a diagram showing the concept of frequency selective fusing and reception environment information generation in the second modification.

[0090] The mobile terminal receives a multi-carrier signal affected by frequency selective fading as shown in FIG. When the SNR estimation unit 47 of the mobile terminal receives a signal sequence corresponding to each subcarrier with respect to the signal affected by the fading, the SNR estimation unit 47 estimates the average SNR of each subcarrier block (hereinafter simply referred to as SNR). . In FIG. 8, each bar (square) represents a subcarrier block. [0091] Feedback information generating section 53 first detects the subcarrier block number having the maximum SNR from the SNRs related to the respective subcarrier blocks (subcarrier block #n in FIG. 8).

 Next, the feedback information generation unit 53 obtains delay dispersion of the received signal. This delay dispersion is obtained by obtaining a delay profile, that is, waveform information in the time axis region (time-received power axis) for the received signal as shown in FIG. The feedback information generating unit 53 obtains the delay dispersion based on the obtained delay profile. The delay dispersion σ can be calculated by the following (Equation 2) when the delay profile is P (t). The reciprocal of this delay dispersion information indicates the SNR dispersion (spread) of the received signal.

 [0093] [Equation 2]

The feedback information generation unit 53 generates reception environment information including the maximum value of SNR (SNR (n)), the subcarrier block number (n), and the delay dispersion information described above.

 [0094] <User assignment process>

 In the base station apparatus, when a signal including the reception environment information (n, SNR (n), σ) described above is received, the reception environment information is extracted by the feedback information extraction unit 23 and is transmitted to the user allocation unit 24. Passed.

 [0095] Upon receiving the reception environment information (n, SNR (n), σ) for each mobile terminal in this way, the user allocation unit 24 receives each subcarrier block for each mobile terminal based on each reception environment information. Estimate each SNR. The estimation of SNR (SNR (k)) for each subcarrier block k other than the maximum SNR is, for example, estimated as shown in (Equation 3) below.

 est

 [0096] [Equation 3]

SNR _est (k) = SNR (n)-

-«|) · ■ · (Formula 3) Here, table (x) may be a value acquired from a table stored in advance in a memory or the like, for example. In this case, the table stores the SNR attenuation amount in relation to the delay carrier σ and the subcarrier block _η having the maximum SNR to the frequency band proximity (k−η) of the target subcarrier block. You may do it.

[0097] In addition, the reduced estimated amount from the maximum SNR may be defined in advance by a function or the like showing a parabola as table (x) = ax ² that of using the table Nag. Information that is stored in advance as a table or used for attenuation calculation that is defined in advance as a function can be adjusted from the outside according to the installation environment of the transmitter, the radio wave propagation environment, etc. You may make it become.

[0098] Then, the user allocation unit 24 holds the estimated information to execute a user allocation process for each mobile terminal. Subsequent user allocation processing is the same as in this embodiment.

<Operation Z Effect in Second Modification>

 In the base station device (transmitting device) and mobile terminal (receiving device) in the second modification, the maximum

In addition to the SNR and its subcarrier block number (n), delay dispersion information σ is notified to the base station apparatus.

 [0100] When the base station apparatus receives the reception environment information from each of a plurality of mobile terminals as communication partners, the SNR of each subcarrier block in each mobile terminal is estimated based on the reception environment information. In the second modified example, for this SNR estimation, the SNR is estimated for the subcarrier block for which the actual SNR is not reported in relation to the maximum SNR and the delay dispersion σ.

[0101] Then, when the SNR of each subcarrier block for each mobile terminal is estimated, transmission should be made to the mobile terminal having a high SNR for each subcarrier block in the transmission signal based on the estimated SNR. Signals are preferentially placed.

[0102] Thus, in this embodiment, the reception environment information notified from each mobile terminal is the maximum S.

In addition to information on NR, delay dispersion information is included.

[0103] Thus, according to the second modified example, the S around the subcarrier block having the maximum SNR.

Since the NR can be notified to the base station device with a small amount of information (three pieces of information), Adaptive frequency allocation based on accurate reception environment information can be realized while reducing the amount of information on the back link.

 [Third Modification]

 In the reception environment information generation method and the user allocation process in the above-described embodiment, the mobile terminal uses a predetermined threshold (XdB), and the differential power of the maximum SNR power is information on the subcarrier block having an SNR within this threshold. In addition to the maximum SNR, the subcarrier block number (n), and the relative SNR relative to the maximum SNR for the subcarrier blocks around the subcarrier block number (n) You may make it notify to a base station apparatus. Hereinafter, the reception environment information generation process of the mobile terminal and the user allocation process of the base station apparatus in the third modification will be described. In addition, the functional configurations of the mobile terminal and the base station apparatus are the same as those in the above embodiment.

 [0105] <Reception environment information generation processing>

 Hereinafter, reception environment information generation processing in the mobile terminal will be described with reference to FIG. FIG. 9 is a diagram showing the concept of frequency selective fusing and reception environment information generation in the third modification.

 [0106] The mobile terminal receives a multi-carrier signal affected by frequency selective fading as shown in FIG. When the SNR estimation unit 47 of the mobile terminal receives a signal sequence corresponding to each subcarrier with respect to the signal affected by the fading, the SNR estimation unit 47 estimates the average SNR of each subcarrier block (hereinafter simply referred to as SNR). . In Fig. 9, each bar (square) represents a subcarrier block.

 [0107] First, feedback information generation section 53 detects the subcarrier block number having the maximum SNR from among the SNRs related to each subcarrier block (subcarrier block #n in Fig. 9).

) o

Next, feedback information generating section 53 calculates SNR difference information from the maximum SNR with respect to the subcarrier block having the peripheral frequency band around the subcarrier block having the maximum SNR. The SNR difference information for each subcarrier block is given as A SNR (k) where A SNR (k) is the SNR difference information for subcarrier block k with respect to subcarrier block n having the maximum SNR. ) = SNR (n) —SNR (k).

 [0109] Feedback information generating section 53 sets the SNR difference information for each subcarrier block calculated as described above to a predetermined number of bits. This bit configuration indicating the SNR difference information may use a fixed bit configuration determined in advance as a system. In the example of FIG. 9, the subcarrier block power having the maximum SNR is also configured so that the number of bits used to indicate the SNR difference information decreases every time a predetermined range (subcarrier block) is left. Showing

 [0110] In this case, the SNR in subcarrier block n having the maximum SNR is indicated by 8 bits, and the SNR difference information is indicated by 3 bits for subcarrier blocks within 3 subcarrier blocks from subcarrier block n. Thereafter, every third subcarrier block is reduced by 1 bit. This can be expressed in subcarrier block k as follows:

[0111] (1) When 0 <I k-n I ≤3,

 A SNR (k) = “000”: OdB or more and less than ldB

 = "001": ldB or more, less than 2dB

= "L l l": 7dB or more

 (2) When 3 <I k-n I ≤6

 Δ SNR (k) = “00”: OdB or more and less than 2dB

 = "01": 2dB or more and less than 4dB

 = "10": 4dB or more, less than 6dB

 = "L l": 6dB or more

 (3) When 6 <I k-n I ≤9,

 Δ SNR (k) = “0”: OdB or more and less than 4dB

 = "L": 4dB or more

 (4) When 9 <I k-n I, reception environment information is not generated.

[0112] <User assignment process>

In the base station apparatus, each of the reception environment information (n, SNR (n), | kn | A signal containing SNR difference information Δ SNR (k)) of the rear block is received.

 Then, the reception information extraction unit 23 extracts the reception environment information and passes it to the user allocation unit 24.

 [0113] Upon receiving the reception environment information for each mobile terminal in this way, the user allocation unit 24 estimates each subcarrier block of I kn I ≤ 9 sections for each mobile terminal based on the reception environment information. To do. At this time, it is assumed that the user allocation unit 24 has grasped the bit configuration for indicating the above-described SNR difference information, and estimates the SNR of each subcarrier block based on the information. The bit configuration indicating the SNR difference information may be stored in advance as fixed information in a memory or the like, or may be mutually notified between the base station apparatus and the mobile terminal as necessary. Also good.

 [0114] Then, the user allocation unit 24 holds the estimated information to execute a user allocation process for each mobile terminal. Subsequent user allocation processing is the same as in this embodiment.

 [0115] <Action in third variation Z effect>

 In the base station device (transmitting device) and mobile terminal (receiving device) in the third modification, in addition to the maximum SNR, the subcarrier block number (n), the subcarrier block having the peripheral frequency band of the subcarrier block number (n) The difference information between the SNR and the maximum SNR related to the carrier block is notified to the base station apparatus.

 [0116] Further, the reception environment information is generated in the state indicated by the predetermined bit configuration as the difference information from the maximum SNR. The third modified example is configured such that the number of bits used every time a predetermined subcarrier block range moves away from the subcarrier block n having the maximum SNR.

 [0117] When the base station apparatus receives the reception environment information of each of a plurality of mobile terminals as communication partners, the SNR of each subcarrier block in each mobile terminal is estimated based on the reception environment information. . This SNR estimation is realized when the base station apparatus knows the bit configuration in which multiple mobile terminals set SNR difference information.

[0118] Then, the SNR of each subcarrier block for each mobile terminal is estimated. Then, based on these estimated SNRs, a signal to be transmitted to a mobile terminal having a high SNR for each subcarrier block in the transmission signal is preferentially arranged.

[0119] As described above, in this embodiment, the reception environment information notified from each mobile terminal is the maximum SNR for the subcarrier blocks around the subcarrier block n having the maximum SNR in addition to the information about the maximum SNR. Is generated by rounding the difference information of SNR with the specified number of bits.

 [0120] Also, as in this embodiment, since the width of one subcarrier block is relatively smaller than the effect of frequency selective fading, the change in SNR of each subcarrier block tends to be moderate. Is used.

 [0121] Thereby, according to the third modification, the SNR around the subcarrier block having the maximum SNR can be notified to the base station apparatus with a small amount of information, so that while suppressing the amount of information on the feedback link, Adaptive frequency allocation based on accurate reception environment information can be realized.

Claims

The scope of the claims

 [1] A plurality of subcarriers are divided into a plurality of subcarrier blocks including at least one subcarrier, and a signal to each receiving apparatus receives a multicarrier signal arranged in the subcarrier block unit. Receiving means for

 Estimating means for estimating each subcarrier block with a quality value indicating a reception state of a signal arranged in each subcarrier block;

 Information indicating a high quality subcarrier block having a high quality value among the quality values, a quality value in the high quality subcarrier block, and a difference between the quality value in the high quality subcarrier block is within a predetermined threshold. A notifying means for notifying a transmitting device of a subcarrier block section having a certain quality value,

 A receiving device.

 [2] The notifying means is a subcarrier block having a quality value whose difference from a quality value in the high quality subcarrier block is within a predetermined threshold, and is the smallest among the subcarrier blocks included in the relevant section. The receiving apparatus according to claim 1, wherein information indicating a subcarrier block having a frequency band and information indicating a subcarrier block having a maximum frequency band are notified.

[3] The notification means includes information indicating the subcarrier block having the minimum frequency band, information indicating the subcarrier block having the maximum frequency band, a quality value in the subcarrier block having the minimum frequency band, and The quality value in the subcarrier block having the maximum frequency band is also notified.

 The receiving device according to claim 2.

[4] The predetermined threshold is notified from the transmission device,

 The receiving device according to any one of claims 1 to 3.

[5] It further comprises dispersion estimation means for estimating the delay dispersion of the received multicarrier signal,

 The notifying means notifies the transmission apparatus of the delay dispersion estimated by the dispersion estimating means instead of the section of the subcarrier block;

The receiving device according to claim 1.

[6] The notification means includes

 The difference between the quality value in the high-quality subcarrier block and the quality value in each subcarrier block is represented by a smaller amount of information in a subcarrier block having a frequency band farther from the high-quality subcarrier block. Further comprising generating means for generating the difference information,

 The receiving apparatus according to claim 1, wherein the difference information is notified to a transmitting apparatus in place of the subcarrier block section.

[7] In a communication system in which a transmitting device and a plurality of receiving devices transmit and receive multicarrier signals having a plurality of subcarrier powers,

 Each of the receiving devices is

 Receiving means for receiving a multicarrier signal that is divided into a plurality of subcarrier blocks including at least one subcarrier power and in which a signal to each receiving device is arranged in units of the subcarrier blocks;

 Estimating means for estimating each subcarrier block with a quality value indicating a reception state of a signal arranged in each subcarrier block;

 Information indicating a high quality subcarrier block having a high quality value among the quality values, a quality value in the high quality subcarrier block, and a difference between the quality value in the high quality subcarrier block are within a predetermined threshold. Notifying means for notifying the transmitting apparatus of a subcarrier block having a certain quality value;

 With

 The transmitter is

Information indicating a high-quality subcarrier block having a high quality value among the quality values, the quality value in the high-quality subcarrier block, and the quality value in the high-quality subcarrier block respectively notified from the reception devices Quality estimation means for estimating a quality value in each subcarrier block related to a notification source receiving device based on a section of subcarrier blocks having a quality value whose difference from a quality value is within a predetermined threshold; Based on the quality value of each subcarrier block estimated for each device, the signal to each receiving device is allocated to each subcarrier block. In addition, an arrangement unit that preferentially arranges a signal to a receiving apparatus having a high quality value with respect to a target subcarrier block;

 Transmitting means for transmitting a multicast signal signal-arranged by the arranging means to the plurality of receiving devices;

 A communication system comprising:

 [8] The receiving device includes:

 Further comprising dispersion estimation means for estimating delay dispersion of the received multicarrier signal;

 The notifying means notifies the transmitter of the delay dispersion estimated by the dispersion estimating means instead of the section of the subcarrier block;

 The quality estimation means of the transmitting device estimates the quality value in each subcarrier block related to the notification source receiving device based on the delay spread instead of the subcarrier block section,

 The communication system according to claim 7.

[9] The notification means of the receiving device includes:

 The difference between the quality value in the high-quality subcarrier block and the quality value in each subcarrier block is represented by a smaller amount of information in a subcarrier block having a frequency band farther from the high-quality subcarrier block. Further comprising generating means for generating the difference information,

 The transmission device is notified of the difference information instead of the subcarrier block interval, and the quality estimation unit of the transmission device is changed to the subcarrier block interval, and is based on the difference information and relates to a notification source reception device. Estimate the quality value in each subcarrier block,

 The communication system according to claim 7.